PCBs can taint building caulk.

Joints around windows and between masonry panels in public buildings erected or renovated during the 1960s and 1970s were often sealed with a caulk containing polychlorinated biphenyls (PCBs). The oily PCBs kept the sealant pliable so that it could expand and contract with the weather. Although the Environmental Protection Agency banned PCBs' production in 1977 owing to the compounds' toxicity, some tainted caulk remains in place. Indeed, Robert F. Herrick of the Harvard School of Public Health in Boston and his colleagues have now found it at 13 of 24 Boston-area buildings they sampled.

In some cases, a caulk's PCB concentration was nearly 1,000 times the amount that would ordinarily trigger a material's immediate removal and, if necessary, the decontamination of the building containing it.

Herrick, an industrial hygienist, consulted members of the local brick-and-masonry union to identify buildings where they remember applying the toxic sealant. The study was funded in part by this union and other building-trades unions.

In the July Environmental Health Perspectives, Herrick and his colleagues report that eight buildings had caulk with PCBs concentrations exceeding EPA's 50 parts per million (ppm) limit. The concentration was above 5,000 ppm in the caulk at a middle school, a high school, and a synagogue, and it exceeded 26,000 ppm in the caulk of several buildings holding government offices, university classrooms, and dorm rooms.

There is no evidence that the PCBs in the caulk have actually caused any health problems. However, studies elsewhere have shown the migration of PCBs from such caulk into adjacent masonry, indoor dust, and people. Herrick's team plans to investigate whether inhaling degraded-caulk dust affects the workers who remove the caulk.--J.R.